O2 sensor and Camshaft Position problems

hi everyone:
I bought a 1996 saturn SL2 from private seller, and then after several days the service engine light was steady on, and I checked from the Auto zone, they told me the O2 Sensor(CKT Slow Response) and Camshaft Position (Sensor A-Bank 1 CKT Range/Perf) were something wrong.. I'm not sure if they are big problems and I have to replace them as soon as possbile,
Anyone can give me some suggestions? maybe I can bought some used parts from Interent?thanks

the O2 sensor needs replaced, inspect old O2 sensor for cause of failure(carbon build-up) and investagate if needed.

the the Cam sensor code - http://www.saturnfans.com/forums/showthread.php?t=43380

Thank you very much, yesterday the service engine light was off, but today it's still on!! I will print the article of "Cam sensor code" and take it to repair center.

the O2 sensor needs replaced, inspect old O2 sensor for cause of failure(carbon build-up) and investagate if needed.

the the Cam sensor code - http://www.saturnfans.com/forums/showthread.php?t=43380

the O2 sensor needs replaced, inspect old O2 sensor for cause of failure(carbon build-up) and investagate if needed.

the the Cam sensor code - http://www.saturnfans.com/forums/showthread.php?t=43380

Can an O2 sensor be cleaned of excess carbon and be functional for an extended period?

every manufactior i know of forbids cleaning of O2 sensors.

Can an O2 sensor be cleaned of excess carbon and be functional for an extended period?
thanxs for the info.